1. Field of the Invention
The present invention relates to a spherical silicon oxycarbide particle material and a manufacturing method thereof. In particular, to a silicon oxycarbide particle material that is used as a lubricant, an abrasive agent or a polymer additive.
2. Description of Related Art
Ceramics generally have the characteristics of excellent heat resistance, high hardness, being lighter than metal, excellent oxidation resistance, and in some cases, can have good solvent resistance, acid resistance or base resistance. Taking advantages of the characteristics and physical properties of ceramics, it has been widely used for many different purposes. In particular, for spherical ceramic particle materials, while having the characteristics of ceramics, the particles may take advantage of its spherical shape to provide improved functions as compared to conventional materials having unevenly distributed shapes and particles. Furthermore, it is also possible to use these spherical ceramic particles for a variety of different purposes. However, spherical ceramic particles are hard to manufacture, and the production cost is high, it is therefore not generally applied.
The present invention is particularly related to a spherical silicon oxycarbide (SiOC) particle material that is comparatively more uniform in particle size and may be sintered at low temperatures, and a manufacturing thereof. More specifically, the spherical silicon oxycarbide particle material may take advantages of the excellent characteristics and physical properties of ceramics, and be useful in solid lubricants, additive for lubricants, abrasive agents and polymer additives that are added to plastics (various fillers such as heat resistance fillers or conductive material fillers, filling agents or dispersion agents).
In the situations where the ceramic particle material are directly used as solid lubricants or abrasive agents, or used as lubricant additives that are added to grease, or used as additive for abrasive agents, or used as polymer additives that are added to plastics (abrasive agents, additives for abrasive agents, polymer additives, various fillers such as heat resistance fillers or conductive material fillers, filling agents or dispersion agents), the physical properties and characteristics such as the particle shape, particle size distribution, and the degree of aggregation of the ceramic particle material may affect the liquidity and formability, and ultimately, affects the uniformity of the molded product. Furthermore, it is well known that the expansion of the product, the contraction anisotropy, warpage or cracks will all have a great impact in affecting the properties of the product. In addition, a more inexpensive industrial production is desired.
More specifically, the particle material may be used as lubricants for lowering the friction coefficient of the sliding portion in various machines or devices such as internal combustion engines, machine tools, logistics machinery and electronic products. By lowering the friction coefficient, the performance of the lubricants may be improved. As such, an improvement in the operation efficiency with prolonged lifetime, in addition, with quietness or vibration reduction can be provided to the machines or devices. Furthermore, low fuel consumption and energy saving may be achieved. Since it is not easy and cheap to provide a ceramic used for lubricants with both particle shape and particle size distribution having the sufficient uniformity, the desired performance improvement is yet to be obtained.
In order to reduce friction of the sliding portion and to reduce energy loss, in the properties of abrasive materials to more precisely polish the surfaces of the sliding members, the bearing parts, and the sliding contact structure members, the five important properties of abrasive materials are hardness, toughness, wear resistance, particle size and particle shape. Furthermore, the particle material's particle shape, particle size distribution and degree of aggregation of the ceramic raw materials used to form the structural member will affect the performance of the product. Therefore, in order to obtain uniform spherical particles, the ceramic raw material is molded to form a product such that the surface roughness is homogenized, and thereby, the surface roughness can be reduced.
However, for surface abrasive agents and additives for abrasive agents, and also for the ceramic raw materials, a homogenous micro-sized ceramic particle material as the raw material being homogeneous in shape and particle size distribution has yet to be obtained. Furthermore, a simple and inexpensive method of manufacturing the ceramic particle material with the desired performance and physical properties has yet to be established.
For the ceramic particle material that are used as abrasive agents, lubricants or additives or alternatively, used as the raw material of the manufactured product, from the perspective of shape uniformity, particle size distribution uniformity and dispersibility, it is desired that the ceramic particle material used is a homogeneous particle material, and for the intended purpose to be spherical having no anisotropy in the micro-sized range. Conventionally, to obtain such ceramic particle material, an increased manufacturing process and a more precise process management are required, wherein the manufacturing cost is compensated.
As an example, a simple manufacturing method to obtain homogeneous ceramic particle material with high sphericity is described (patent document 1). The method includes obtaining spherical silicon carbide micro-particles by performing a sintering process of poly-organocarbosilane in an inert atmosphere at 1400 to 1600° C. Although the method can be used to obtain ceramic particles with high sphericity, the poly-organocarbosilane raw material is relatively expensive, and the device cost and running cost for performing the sintering process at 1400 to 1600° C. will also be a problem.
On the other hand, silicon oxycarbide (SiOC) has similar properties with silicon carbide. However, as a precursor of organic silicon polymers, the raw materials such as polysiloxane and polysilsesquioxane can be obtained at a cheaper price, wherein the sintering process temperature can be about 800-1200° C., which is economically more favorable.
The methods for obtaining spherical silicon oxycarbide particle material have been described (non-patent document 1-3).
In non-patent document 1, a method to obtain spherical silicon oxycarbide particles in the range of 10-100 μm is reported. However, in this method, the particle size distribution is wide and a problem exists where it contain cracks in the particle.
In non-patent document 2, a spherical silicon oxycarbide having uniform particle size is reported. However, in this method, the particles are connected together and have bad dispersibility, wherein if the particles are made to be single particles, this results in silicon oxycarbide micro-particles having low sphericity.
In non-patent document 3, spherical silicon oxycarbide micro-particles having no cracks or aggregation are reported. However, in this method, particles can only be obtained around 300 nm, wherein silicon oxycarbide particles controlled to have larger particle size has not yet been obtained.
In any of the described methods, spherical silicon oxycarbide particle material which are micro-sized particles useful for manufacturing products such as abrasives, lubricants or additives having a uniform particle size and no aggregation for obtaining a homogenous product cannot be obtained.